Commit bfeb022f authored Apr 10, 2020 by Logan Gunthorpe Committed by Linus Torvalds Apr 10, 2020

mm/memory_hotplug: add pgprot_t to mhp_params



devm_memremap_pages() is currently used by the PCI P2PDMA code to create
struct page mappings for IO memory.  At present, these mappings are
created with PAGE_KERNEL which implies setting the PAT bits to be WB.
However, on x86, an mtrr register will typically override this and force
the cache type to be UC-.  In the case firmware doesn't set this
register it is effectively WB and will typically result in a machine
check exception when it's accessed.

Other arches are not currently likely to function correctly seeing they
don't have any MTRR registers to fall back on.

To solve this, provide a way to specify the pgprot value explicitly to
arch_add_memory().

Of the arches that support MEMORY_HOTPLUG: x86_64, and arm64 need a
simple change to pass the pgprot_t down to their respective functions
which set up the page tables.  For x86_32, set the page tables
explicitly using _set_memory_prot() (seeing they are already mapped).

For ia64, s390 and sh, reject anything but PAGE_KERNEL settings -- this
should be fine, for now, seeing these architectures don't support
ZONE_DEVICE.

A check in __add_pages() is also added to ensure the pgprot parameter
was set for all arches.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Eric Badger <ebadger@gigaio.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Link: http://lkml.kernel.org/r/20200306170846.9333-7-logang@deltatee.com


Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 4e00c5af

arch/arm64/mm/mmu.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -1382,7 +1382,8 @@ int arch_add_memory(int nid, u64 start, u64 size,
		flags = NO_BLOCK_MAPPINGS \| NO_CONT_MAPPINGS;

		__create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start),
		size, PAGE_KERNEL, __pgd_pgtable_alloc, flags);
		size, params->pgprot, __pgd_pgtable_alloc,
		flags);

		memblock_clear_nomap(start, size);

arch/ia64/mm/init.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -676,6 +676,9 @@ int arch_add_memory(int nid, u64 start, u64 size,
		unsigned long nr_pages = size >> PAGE_SHIFT;
		int ret;

		if (WARN_ON_ONCE(params->pgprot.pgprot != PAGE_KERNEL.pgprot))
		return -EINVAL;

		ret = __add_pages(nid, start_pfn, nr_pages, params);
		if (ret)
		printk("%s: Problem encountered in __add_pages() as ret=%d\n",

arch/powerpc/mm/mem.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -132,7 +132,8 @@ int __ref arch_add_memory(int nid, u64 start, u64 size,
		resize_hpt_for_hotplug(memblock_phys_mem_size());

		start = (unsigned long)__va(start);
		rc = create_section_mapping(start, start + size, nid, PAGE_KERNEL);
		rc = create_section_mapping(start, start + size, nid,
		params->pgprot);
		if (rc) {
		pr_warn("Unable to create mapping for hot added memory 0x%llx..0x%llx: %d\n",
		start, start + size, rc);

arch/s390/mm/init.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -277,6 +277,9 @@ int arch_add_memory(int nid, u64 start, u64 size,
		if (WARN_ON_ONCE(params->altmap))
		return -EINVAL;

		if (WARN_ON_ONCE(params->pgprot.pgprot != PAGE_KERNEL.pgprot))
		return -EINVAL;

		rc = vmem_add_mapping(start, size);
		if (rc)
		return rc;

arch/sh/mm/init.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -412,6 +412,9 @@ int arch_add_memory(int nid, u64 start, u64 size,
		unsigned long nr_pages = size >> PAGE_SHIFT;
		int ret;

		if (WARN_ON_ONCE(params->pgprot.pgprot != PAGE_KERNEL.pgprot)
		return -EINVAL;

		/* We only have ZONE_NORMAL, so this is easy.. */
		ret = __add_pages(nid, start_pfn, nr_pages, params);
		if (unlikely(ret))

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